Skip to navigation. Black holes, cosmology, gravitational waves - our "Spotlights on Relativity" section invites you to take a look at some of the many facets of relativity. The following is a complete list of all our current spotlight texts. All but a few of these texts are completely independent of each other, so you can browse to your heart's content - it would help, however, if you already had some previous ideas about relativity, on the level of our introduction Elementary Einstein. More about the foundations and applications of special relativity. How motion influences waves, or other kinds of ever-repeating signals, in classical physics and in special relativity.

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How relativity can reconcile statements that, at first glance, appear to be contradictory. More about simultaneity, time dilation and the famous case of the travelling twin. Why it is necessary to define simultaneity, and how best to go about defining it. How you can picture the relativity of simultaneity and time dilation, using a simple geometric analogy. Why the so-called "twin paradox" isn't really a paradox. How one can picture the situation of the travelling twin, using a simple geometric analogy.

Some background information about the most famous formula in all of physics. Why Einstein's famous formula tells us that the whole, as far as mass is concerned, is often less than the sum of its parts. The subtle connections between Einstein's formula, nuclear fission and nuclear fusion. Concepts and applications of general relativity. Information about the principle that Einstein took as a starting point for developing his general theory of relativity. So what is gravity in Einstein's theory?

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The answer: in part, an illusion; in part, an aspect of geometry. Why, in general relativity, all observers are on an equal footing - and why, nevertheless, you can say that the earth orbits the sun, but not the other way around. An account of which physical properties act as sources of gravity - includes consequences for collapsing stars and for cosmology. An important property of gravity in Einstein's theory is that it can create more gravity. The result is "non-linearity" - the gravitational influence of two bodies isn't just the sum of their separate influences!

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On one of the fundamental consequences of general relativity: the deflection of light by gravity. The connection between one of the fundamental principles of general relativity and the gravitational deflection of light.

## Relativity

Historical sketch of the derivation of general relativity's prediction of gravitational lenses and subsequent astronomical observations. One of the fundamental effects predicted by general relativity, and some of its astronomical applications. Information about the most disturbing feature of Einstein's theory - ragged edges of spacetime known as singularities. About some characteristic properties of spacetime near singularities - and the violent deformations they cause for any object unlucky enough to approach a singularity.

Modeling relativistic fluids and the phenomena associated with them - from supernovae and jets to merging neutron stars. Information about a modification of Einstein's theory of general relativity in which the gravitational constant is not a constant. Most readers will know them from childhood: soap bubbles.

More information on one particular answer to the question of how much variety is permitted in general relativity - how many ways are there of constructing a universe that is completely empty of all matter? An overview of Nobel prizes connected with relativistic physics. More about gravitational waves, how they are produced and how they can be detected.

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A closer look at the way that simple gravitational waves propagate through space with time. For some gravitational wave signals, one can go beyond graphs and animations - they can be made audible. White Dwarf binaries, their properties, and the role they will play for the planned space-borne gravitational wave detector LISA. More about gravitational wave detectors on earth and in space. Overview of the gravitational wave detectors currently operational, or under construction. Informations about how you personally can help with the search for gravitational wave - by donating processing time on your private computer.

Some information on how the vintage models among gravitational wave detectors work - resonant detectors. Information about the latest version of the most ambitious gravitational wave project - a detector in space. One hundred years ago, Albert Einstein predicted in his general theory of relativity the existence of gravitational waves. These ripples in space-time propagate at the speed of light and were directly observed for the very first time on September 14, Information about a class of simple model universes, each an expanding cosmos filled with gravitational waves. Black holes, neutron stars and supernovae: Flight into a black hole, the black hole in the center of the Milky Way, how many different kinds of black hole are there, how black holes light up their neighbourhood.

The story of an expedition's closer and closer approach to a black hole - too close? More about the gravitational influence of black holes and neutron stars on their cosmic surroundings, from the orbits of nearby stars to accretion disks and the associated luminous phenomena. Information about the closest supermassive black hole - the central object of our own galaxy. How the fact that black holes are very efficient in attracting surrounding matter leads to some of the most spectacularly luminous phenomena in the whole of the cosmos.

What astronomers can see once a black hole has heated up its cosmic neighbourhood, stimulating it to emit bright radiation. Once they have settled down, there are actually only very few different kinds of black hole - find out which, and how black holes shed other distinguishing marks. The intriguing possibility that the next generation of particle accelerators might produce - and allow the detection of - miniature black holes.

How, in one sense, space and time switch their roles inside a black hole - and why this leads to a black hole's most characteristic property, namely that nothing can get out. Some information about what is called the conservation of angular momentum, and its consequences for neutron stars, black holes and the matter disks around them. The connection between temperature and the emission of electromagnetic radiation, as well as the consequences for stars, matter disks around black holes, and cosmology.

The big bang and all the rest: The geometry of the universe, the formation of the first light chemical elements, cosmology and quantum gravity. In cosmology, "big bang" has two different meanings - and if you want to understand what's going on, you should be aware of that difference.

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The different space geometries allowed by the big bang models - do we live on a hypersphere? Why cosmology is not only a matter for astronomers and physicists, but also for mathematicians. How the spatial geometry of the universe can be derived by observing the cosmic background radiation. How the first nuclei of helium, lithium and other light elements were cooked up shortly after the big bang. The physics behind Big Bang Nucleosynthesis, the period shortly after the big bang that saw the first production of light elements such as helium and lithium. How to reconstruct the abundances of light elements shortly after the big bang, and thus test some important predictions of the big bang models against observation.

More information about possible cosmological consequences of the attempts to formulate a theory of quantum gravity. About attempts to understand the beginning of our universe using different approaches to quantum gravity. The collapsing and then re-expanding quantum universe that loop quantum gravity offers as a replacement of the standard big bang models.

How loop quantum gravity could replace the absurd state of infinite density, the big bang with which, according to Einstein's relativity, the universe began. Relativistic quantum theory, string theory, loop quantum gravity and other attempts to unify Einstein's gravitation with quantum theory; the uses of extra dimensions; quantum gravity and the big bang. Some aspects of quantum gravity that are independent of which of the possible approaches is chosen. The principle of background independence - space and time are no fixed structure, but take part in the dynamical evolution of the world - and its consequences for the problem of quantum gravity.

More about string theory - at present, mostly about the extra dimensions that play such a central role in that theory. Why our universe could possess dimensions beyond length, width and depth - and why those dimensions need not be noticeable in everyday life. Is our three-dimensional world embedded in a higher-dimensional space? Ways of detecting extra dimensions - and why the fact that our earth orbits the sun is a relevant data point.

## MATH | Relativity, Black Holes and Cosmology | University of Southampton

Why matters that seem rather complicated might be much more simple in higher dimensions. More about loop quantum gravity, in particular its cosmological applications. The quantum structure of space according to loop quantum gravity. While string theory and loop quantum gravity are the most prominent approaches to the problem of quantum gravity, they are not the only ones.

Some other approaches are described in the following spotlights. An overview of the causal set approach to a theory of quantum gravity.

Useful physics background information that may help with a better understanding of the other spotlight texts on this page. About the path integral approach to quantum theory. Legal notice Impressum Datenschutzhinweis. Main Navigation Home. Elementary Einstein. Spotlights on relativity.

Special relativity.

General relativity. Gravitational waves.